by Gary L Wenk
Are spices good for my brain?
Cinnamon is a spice obtained from the bark of the Cinnamomum verum tree. Since antiquity, it has had many uses. Moses included it as an ingredient of the holy anointing oil. The Chinese knew it as Gui Zhi and recommended it for its antibacterial and antipyretic properties. Medieval physicians included cinnamon in their preparations to treat arthritis and infections. (The widespread use of willow tree bark [and the aspirin-like chemical that was derived from it] for these ailments was still a thousand years in the future.) A recent study found that eating cinnamon might prevent a variety of age-related neurological disorders. How does this happen? The sodium benzoate produced in the body after eating cinnamon induces significant increases in the levels of a variety of chemicals in the brain called neurotrophic factors. These factors stimulate the birth of new neurons in the brain and encourage the survival of existing neurons. These two processes are critical for the maintenance of a healthy brain. During the past decade, many scientific studies have discovered that these neurotrophic factors can prevent, or greatly slow, the progression of a variety of degenerative diseases of the brain, including Alzheimer’s and Parkinson’s disease. Cinnamon also can reduce blood sugar levels slightly in people with type II diabetes and reduce cholesterol levels by up to 25%. Thus, cinnamon is good for your brain and body.
Curcumin, derived from the spice turmeric, the powdered rhizome of the medicinal plant Curcuma longa, has been used for many centuries throughout Asia and India as a food additive and a traditional herbal remedy. Studies have shown that curcumin has potent antioxidative and anti-inflammatory proclivities that may be beneficial for patients with Alzheimer’s or Parkinson’s disease. Treatments with natural antioxidants and anti-inflammatories through diet or dietary supplements are becoming attractive alternatives. Epidemiological and research findings strongly indicate that the solution to healthy aging is exactly what you have heard from your mom: Eat healthy and in moderation; exercise in moderation.
Let food be thy medicine and medicine be thy food.
—Hippocrates (460–370 B.C.E.)
During the past 2,500 years since the time of Hippocrates, science has made significant progress in understanding how food exerts its beneficial effects on health. We now have solid proof that the foods and beverages that are consumed by humans, in particular those derived from tea leaves, coffee and cocoa beans, celery, grapes, mangos, berries, hops, and other grains, have clearly defined beneficial effects on brain function. Although these foods and drinks have quite different chemical compositions, they all contain compounds called flavonoids. Flavonoids are not in themselves nutritious, but they are believed to be responsible for the beneficial effects of many foods on the brain.
How do flavonoids benefit us?
In order to answer this question, scientists have investigated what flavonoids can do when their concentration in the brain is extremely low, that is, at levels that are likely achieved by a diet rich in these fruits. The flavonoids directly induce neurons in the brain to become more “plastic”—that is, more capable of forming new memories. The flavonoids achieve this by directly interacting with specific proteins and enzymes that are critical for learning and memory. They also induce the birth of new neurons, a process that is critical for recovery from injury, exposure to toxins, and the consequences of advanced age, such as increased levels of brain inflammation. Finally, some recent studies have shown that flavonoids actually enhance blood flow to active brain regions and thereby allow enhanced neuronal function.
So how much is enough? Let us consider two of our common favorites: wine and chocolate. If you consumed about 200 milliliters (6.7 ounces) of Cabernet Sauvignon or about 50 grams (1.7 ounces) of dark chocolate (71% cocoa powder), you would take in nearly identical quantities of flavonoids, which, fortunately, is now the daily wine intake recommended to produce the most health benefits in a typical adult. When young adult females were given flavonoid-rich chocolate drinks, blood flow to their brains significantly increased within just two hours, and their performance on a complex mental task greatly improved. No one is certain whether all flavonoids are capable of producing these benefits. Recent investigations have suggested that it does not matter which type of food provides the flavonoids, only that you should eat them as often as possible. In addition to those edibles mentioned above, studies to date also have identified benefits from black currants, pears, blueberries, strawberries, and grapefruit. You might have noticed that all of these healthy choices are darkly colored—their color is what makes them so valuable to your body. One final caveat: No studies have yet proven a true cause-and-effect connection between the lifelong consumption of flavonoid-rich diets and a reversal of age-related deterioration in learning or general mental function. Still, just in case, it might be worth modifying your diet accordingly (e.g., eating more chocolate).
Eat chocolate!
In 1648, according to the diary of English Jesuit Thomas Gage, the women of Chiapas Real arranged for the murder of a certain bishop who forbade them to drink chocolate during mass. In an ironic twist, the bishop was ultimately found murdered after someone had added poison to his daily cup of chocolate. Was this an act of blind rage by the women of Chiapas Real or justifiable homicide? For a small percentage of the population, eating chocolate can produce rage, paranoia, and anger that occur without warning. Fortunately, for most of us, this is not the typical reaction to eating chocolate. In order to understand why chocolate is so enjoyable for some while it induces uncontrollable rage in others, we need to consider the contents of most dark chocolates. Chocolate contains an array of compounds that contribute to the pleasurable sensation of eating it. Many of these compounds are quite psychoactive if they are able to get into our brains. Are they the reason we love chocolate so much? Are they the reason some people fly into fits of anger? The answer to both questions is, of course, yes. However, as is true for so many of the things we eat that affect our brain, it is not all that simple.
Chocolate usually contains fats that may induce the release of endogenous molecules that act similarly to heroin and produce a feeling of euphoria. German researchers reported that drugs that are able to block the actions of this opiate-like chemical produced by eating chocolate prevented the pleasure associated with eating chocolate. Chocolate also contains a small amount of the marijuana-like neurotransmitter called anandamide. Although this molecule can easily enter the brain, the levels in chocolate are probably too low to produce an effect on our mood by themselves. Chocolate contains some estrogen-like compounds, a fact that may explain a recent series of reports showing that men who eat chocolate live longer than men who do not eat chocolate. (The effect was not seen for women, who have an ample supply of their own estrogen until menopause.)
Let us focus on those women of Chiapas Real again. In contrast to its effects on men, women more often claim that chocolate can lift their spirits. In a study of college students and their parents, 14% of sons and fathers and 33% of daughters and mothers met the standard of being substantially addicted to chocolate. Women seem to have very strong cravings for chocolate just prior to and during their menstrual cycle. Women eat more chocolate in the days before the start of their period when progesterone levels are low. This is when premenstrual symptoms tend to appear as well. Chocolate may provide an antidepressant effect during this period. In one study, researchers found that women in their fifties often develop a sudden strong craving for chocolate. It turns out that most of the women had just entered menopause and were on a standard form of estrogen replacement therapy consisting of 20 days of estrogen and 10 days of progesterone. The chocolate cravings developed during the days on progesterone.
Chocolate contains magnesium salts, the absence of which in elderly females may be responsible for the common postmenopausal condition known as “chocoholism.” About 100 milligrams of magnesium salt is sufficient to take away any trace of chocoholism in these women, but who would want to do that? Finally, a standard bar of chocolate
contains as many antioxidants as a glass of red wine. Clearly, there are many good reasons for men and women to eat chocolate to obtain its indescribably soothing, mellow, and yet euphoric effect.
Okay, what about the anger? How might that happen? Chocolate contains phenethylamine (PEA), a molecule that resembles amphetamine and some of the other psychoactive stimulants. When chocolate is eaten, PEA is rapidly metabolized by the enzyme monoamine oxidase (MAO). Fifty percent of the PEA you consume in a chocolate bar is metabolized within only 10 minutes. Therefore, very little PEA usually reaches the brain, thus contributing little or no appreciable psychoactive effect. However, the amount of PEA in the brain might reach noticeable levels if MAO levels are low. Thus, it might not be a coincidence that MAO levels are at their lowest level in premenstrual women when they most crave the soothing effects of chocolate.
Chocolate also contains small amounts of the amino acid tyramine. Tyramine can powerfully induce the release of adrenaline, increase blood pressure and heart rate, and produce nausea and headaches. Usually, the nasty effects of tyramine are prevented because MAO metabolizes it, too. You can see the problem: The tyramine and PEA in chocolate may slow each other’s metabolism. The consequence is that if both of these chemicals hang around too long in the body, high blood pressure, a fast-beating heart, heightened arousal, racing thoughts, anger, anxiety, and rage would ensue. One rather controversial study claimed that inhibitors of MAO were able to increase PEA levels in the brain 1,000-fold! That is a lot, and the consequences of this actually happening could be lethal. Nevertheless, the potential exists for some vulnerable people to experience significant shifts in mood after eating chocolate with high cocoa powder levels.
The main point to take away from this discussion about chocolate is that plants, such as the pods from the cocoa tree, contain a complex variety of chemicals that, when considered individually, are not likely to impact our brain function. When considered in aggregate, however, they may exert compound effects throughout the body; some of those effects may be desirable, while others may not. Chocolate is yet another excellent example of how difficult it is to differentiate food from drugs.
Brain toxins in the diet
Foods are full of toxins and nutrients; however, this is only from our human perspective, not the plants’ perspective. The overwhelming percentage of toxic substances we consume exist naturally in the plants we consume. Indeed, most of the chemicals humans consider nutritious occur in the same parts of the plants that we consider toxic. Toxins and nutrients are byproducts of the plant living its plant life. We evolved the ability to defend ourselves from these toxins as long as the levels were not too high. Plants absorb lots of different molecules from the land in which they are growing. Some of these can interact with our brain. One famous example is aluminum. Aluminum is everywhere around us all of the time. It is the most abundant metal in the Earth’s crust. Yet, somehow, we have become fearful of it when it is used as cookware, as cans for beer or sodas, or as deodorants. As far as anyone can currently determine, no plants or animals need it for any biological purpose. The reason is that aluminum is highly reactive and easily combines with other metals and oxygen to form hundreds of different minerals. Aluminum, in scientific terms, is not bioavailable to humans—usually. It all depends upon what chemical form the aluminum takes on. Usually, because aluminum is so tightly bound within minerals, animals have no chance to absorb it into their tissues.
This all changed a century ago due to the burning of certain types of coal for energy. In addition, anyone over a certain age will remember the fears associated with acid rain. Although the consequences of having elevated levels of sulfur dioxide and nitrogen oxides in the air have been known since the beginning of the Industrial Revolution, public awareness peaked in the 1970s due to the appearance of “dead lakes,” the destruction of entire forests, and the pitting of marble statues in the United Kingdom and Europe. A century of acidic rains settled into the soil and changed the chemistry of minerals containing aluminum.
Plants do not use aluminum, but they are capable of absorbing it from the soil. Grains that are harvested today to make breads and cereals often contain a few parts per million of aluminum. However, the aluminum in grains unfortunately exists within a bioavailable form, that is, a chemical form that we humans can absorb into our bodies and deposit in tissues. Animals who eat these plants concentrate the aluminum in their tissues, too. Thus, meats obtained from cows may contain up to 1,000 parts per million of aluminum. This is where things get a little dicey. Are we at risk from the aluminum in our diet? As was true for drugs, it depends entirely upon how much one consumes.
Some people are vulnerable to the presence of aluminum in the body. For example, a few years ago people undergoing dialysis began using water containing high levels of aluminum. Over time the levels of aluminum in their brains and bodies began to increase and produced changes in their behavior that resembled dementia. The aluminum deposited within some brain cells caused those cells to die. Fortunately, dialysis centers are aware of this risk and have taken steps to prevent the problem from occurring again. Aluminum does not cause Alzheimer’s disease, although it has been found in the brains of patients who have died with Alzheimer’s disease. Although this seems suspicious, aluminum salts will deposit in any soft tissue that has cell loss due to injury or degeneration. For example, aluminum salts also will accumulate in the hearts of people with coronary disease.
What about deodorants? The aluminum salts used in these products do one thing—they irritate our sweat glands to the point that they swell and close the pores that allow perspiration to reach the surface of our skin. Essentially, aluminum prevents its own absorption by doing so. The real risk from deodorants comes from using sprays that produce a cloud of aluminum salts that can be inadvertently inhaled. Thus, keep using your aluminum cookware—it poses no risk to health.
4
WHY DO I SLEEP AND DREAM?
Our bodies are full of rhythms that are controlled by the brain. Why? A clue to the answer lies in the fact that these rhythms closely follow the rhythms of our planet. Our many biological rhythms exist and are so vital to our survival because we evolved on a spinning planet. For the past 3.5 billion years the most constant and reliable signal to all evolving plants and animals was the regular appearance of the sun on the eastern horizon. During the course of evolution, brains—no matter how simple or complex—always experienced a highly reliable pattern of light and darkness. We call this pattern of day–night cycling the circadian rhythm. Today, after 3.5 billion years of sunrises, our bodies have established a reliable routine: When the sun rises, your eyes inform your brain that it is time to prepare your body for the day’s activities related to survival and procreation. Then, after the sunlight has receded in the West, and after a long day of being awake, your brain prepares you to fall asleep.
What is sleep?
What is it about being awake that leads to a deterioration of normal brain function? This chapter will explore why mental fatigue, poor attentional and decision-making capabilities, impaired learning, and a heightened risk of migraine headaches and epileptic seizures occur as a consequence of sleep deprivation. Sleep is critical to our overall health. Studies have shown that complete insomnia ultimately leads to death in humans, rats, and flies alike.
Each 24-hour day your brain has a choice of three highly distinct phases of consciousness that it can inhabit: (1) wakefulness and (2) dream sleep are periods of time when your brain is quite active; (3) nondream sleep (also called slow wave sleep) is a period when your brain’s activity level is very low.
It is currently thought that the first appearance of the pattern of sleep that we humans are familiar with, that is, a cyclic balance between dreaming and nondreaming sleep, may have appeared in mammals about 150 million years ago. Prior to that ancient time, the brain was either in an active or inactive state. If this is true, the implication is that dinosaurs never dreamed. Dreaming required that the evolving brain find
a way to achieve a good balance among time spent awake, time spent in nondreaming sleep, and time spent in dream sleep. For some animals, maintaining a good balance among wakefulness, dream sleep, and nondream sleep can be quite challenging. For example, seagoing mammals that must constantly be swimming or flying place one hemisphere into deep sleep while the other hemisphere remains wide awake. Dolphins, for example, must keep swimming and coming to the surface to breathe and thus can never place both sides of their brains into deep sleep.